There are two aspects that are equally important in a human/dog relationship, if the human aims to be the leader.
One is protection; the other resource control.
Another word for resource is motivator, drive or reward. It is anything your dog wants at the moment, which means it can change from dog to dog and circumstance to circumstance.
If you can control your dog's drive you control the dog without ever having to use aversive methods and tools.
Positive reinforcement and reward based training is not about food - in fact, more likely than not a well fed dog wants something else more than a treat and only takes the treat because he can't have the other thing. When I am in the woods with my pooches and there are squirrels and rabbits there is no second guessing what they want - it ain't a cookie.

So, the most powerful leaders in the eyes of a dog are the ones that are aware of what he really wants and make it available whenever possible. And often it is possible, but not made available because the owner is too lazy to figure out what the dog is passionate about and not savvy or caring enough to know what she wants at the moment. For example, your insecure companion might be afraid in a group class around other dogs but holding it together because he is trained and wants to please you. You might food reward him for remaining calm, but the better reward would be to increase the distance to the dog(s) that frighten him.

If positive reinforcement trainers could stop to be walking food dispenser and teach their clients to understand their dog, the concept would be an easier sell to many folks still convinced that reward based training equals bribery and spoils the dog.

And, by the way, every dog is passionate about something, but with some dogs it'll take a bit longer to figure out what it is. I worked with a field Labrador once who had, like many dogs bred to work and sold as pets, a one track mind and drove her owners crazy. She was more or less not interested in me either - until I went into the fields with her on a 30 foot lead and found a dead rodent before she did. I pointed it out and let her have it. From that moment on she was "on me" and we could begin training.

Finding what floats your dog's boat is not only fun, but it'll strengthen your bond, your dog will be more attentive and connected and consequently better behaved.